The present invention relates to sealed, water-soluble containers made of polymer films for preserving chemicals, and to the use thereof for the preparation of formulations for different fields of use, especially for formulations for the application of agrochemicals.
Water-soluble containers made of polymer films into which chemicals are filled and which permit the application of chemicals, while avoiding contact therewith, are known. However, polymer films that are commonly used for such containers exhibit failings, typically air pockets, small pores or entrapped dust and other particles. In addition, these polymer films tend to become brittle at low temperature or as a result of the plasticisers present in the film leaching out. Containers made of such polymer films are, therefore, susceptible to damage resulting from mechanical stress during storage and on handling and application. Furthermore, the chemicals in the container can leak through pores or fine cracks in the film and contaminate the environment.
To counteract these problems, it has already been proposed to use a laminated film for fabricating such containers, i.e. a polymer film obtained by pressing together two or more originally separate layers by pressure, heat, crosslinking, fusing or bonding. In these laminated films consisting of a plurality of sheets integrally joined together the occurrence of permanent pores is statistically very insignificant and the strength of the film is enhanced by the layers joined together. A container which is fabricated by using such films is disclosed, inter alia, in DE-OS-41 13 786.
It is, however, very much more troublesome to make laminated films than single layer films, as they are obtained in a second process step from prefabricated monofilms by pressure, heat, crosslinking, fusing or bonding. Laminating requires either additional adhesives or energy in the form of pressure or heat. The fabrication of laminated films is therefore far more cost-intensive than that of monofilms.
It is therefore the object of this invention to provide sealed, water-soluble containers of superior strength and impermeability which are inexpensive and technically simple to manufacture.